Northern silky oak

• Large tree grows to 40m high.
• Stem grows to 2m diameter.
• Trunk, usually without buttresses, is normally straight.
• Bark is slightly flaky to non-descript.
• Outer blaze is commonly biscuit-brown.

• Distribution is limited to North Queensland between Mt Spec, near Townsville, and Bloomfield.

Colour

• Heartwood is pale pink to brown.
• Sapwood is usually almost white.

Grain

• Texture is moderately coarse and varies.
• Quarter-sawn timber best shows the decorative grain.

• Construction: used extensively, in the past, in North Queensland general house framing, cladding, lining, moulding, joinery (particularly windows) and flooring; now confined more to use in joinery.
• Decorative: plywood, furniture, outdoor furnishings, joinery, shop and office fittings, turnery, carving, inlay work.
• Others: used, in the past, for boat building (light), brushware, gunstocks, cooperage, vehicle and coach building.

• Density: 560kg/m³ at 12% moisture content; about 1.8m³ of seasoned sawn timber per tonne.
• Strength groups: S6 unseasoned, SD7 seasoned.
• Stress grades: F4, F5, F7, F8 (unseasoned); F5, F7, F8, F11 (seasoned) when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes.
• Joint groups: J4 unseasoned, JD4 seasoned.
• Shrinkage to 12% MC: 4.7% (tangential), 1.6% (radial).
• Unit shrinkage: 0.31% (tangential), 0.13% (radial)—these values apply to timber reconditioned after seasoning.
• Durability above-ground: Class 4 (life expectancy less than 7 years).
• Durability in-ground: Class 4 (life expectancy less than 5 years).
• Lyctine susceptibility: untreated sapwood susceptible to lyctid borer attack.
• Termite resistance: not resistant.
• Preservation: sapwood readily impregnates with preservative but the heartwood can’t be adequately treated using currently available commercial processes.
• Seasoning: satisfactorily dries using conventional air and kiln seasoning.
• Hardness: soft (rated 5 on a 6-class scale) to indent and work with hand tools.
• Machining: machines, and turns well, to a smooth surface.
• Fixing: no difficulty using standard fittings and fastenings.
• Gluing: satisfactorily bonds using standard procedures.
• Finishing: readily accepts paint, stain and polish; you may need to fill the open grain before polishing the timber.

General characteristics

• Sapwood: creamy white.
• Heartwood: pink to pinkish-brown..
• Texture: coarse and irregular, a broad ray figure (pattern) on quarter-sawn surfaces, straight grain.

Wood structure

• Growth rings: indistinct.
• Vessels: large, numerous, solitary or in short tangential hoops between the rays; no tyloses, but occasionally vessels are filled with whitish deposits or red-coloured gum.
• Parenchyma (soft tissue): abundant, aliform and confluent, including vessels between rays; forming loops, generally, concave outwards; an occasional short tangential apotracheal band.
• Rays: 2 distinct kinds are (a) broad to very broad, plainly visible without a lens on all surfaces, and (b) fine, indistinct even under hand lens.

Other features

• Burning splinter test: match-size splinter burns to charcoal.
• Splinter shape: fine needle-like splinters produced when cutting across the grain are characteristic of this species and can be used to separate northern silky oak from similar species.

• Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, Forest trees of Australia, 5th edn, CSIRO Publishing, Collingwood Australia.
• Bootle, K 2005, Wood in Australia: Types, properties and uses, 2nd ed., McGraw-Hill, Sydney.